1. Field of the Invention
The present invention relates to hydraulic-pneumatic flotation apparatus and method and more particularly to improvements for increasing efficiency of operation.
2. Description of the Prior Art
Commercially valuable minerals, for example, metal sulfides, apatitic phosphates and the like, are commonly found in nature mixed with relatively large quantities of gangue materials, and as a consequence it is usually necessary to beneficiate the ores in order to concentrate the mineral content thereof. Mixtures of finely divided mineral particles and finely divided gangue particles can be separated and a mineral concentrate obtained therefrom by well known froth flotation techniques. Broadly speaking, froth flotation involves conditioning an aqueous slurry or pulp of the mixture of mineral and gangue particles with one or more flotation reagents which will promote flotation of either the mineral or the gangue constitutents of the pulp when the pulp is aerated. The conditioned pulp is aerated by introducing into the pulp a plurality of minute air bubbles which tend to become attached either to the mineral particles or to the gangue particles of the pulp, thereby causing these particles to rise to the surface of the body of pulp and form thereat a float fraction which overflows or is withdrawn from the flotation apparatus.
Typical such flotation apparatus is disclosed in U.S. Pat. No. 3,371,779. In operation, the conditioned pulp is introduced into a flotation compartment containing a relatively quiescent body of an aqueous pulp, and aerated water is introduced into the lower portion of the flotation compartment through suitable orifices. A body of aerated water is provided in an aeration compartment disposed directly below the flotation compartment, a multitude of fine air bubbles being dispersed throughout the water therein. This body of aerated water is in fluid communication with the aqueous pulp in the lower portion of the flotation compartment through the aforementioned orifices. An overflow fraction containing floated particles of the pulp is withdrawn from the top of the flotation compartment and underflow or non-float fraction containing non-floated particles of the pulp is withdrawn from the lower portion of the flotation compartment.
This underflow includes water and non-float fraction. It is conventional to discharge this underflow to waste thereby resulting in the loss of the water. It is the recovery of this wasted water and chemicals which may be contained therein to which the present invention is directed.
Other prior art relating to the concentration of minerals by flotation is disclosed in Hollingsworth Application Ser. No. 145,130, filed May 5, 1980, now U.S. Pat. No. 4,287,054, and U.S. Pat. Nos. 2,753,045 and 3,298,519.